Humidity control devices have been conventionally known that use a hygroscopic liquid such as lithium chloride (LiCl) to control the humidity, as described in Japanese Patent Laid-Open Application No. Hei 11-37514, Japanese Patent Laid-Open Application No. 2005-214595, and the like. A humidity control device using a hygroscopic liquid has: a processor for performing a process of taking in air from a target space, dehumidifying or humidifying the taken-in air, and returning the air to the target space; and a regenerator for regenerating the hygroscopic liquid used by the processor.
A hygroscopic liquid of a high solution concentration absorbs moisture as the temperature decreases, and a hygroscopic liquid of a low solution concentration releases moisture as the temperature increases. Taking advantage of this nature, a humidity control device controls the humidity and regenerates a hygroscopic liquid by controlling the temperature of the hygroscopic liquid to be supplied to the processor and regenerator. Here regenerating a hygroscopic liquid means to restore the concentration of the hygroscopic liquid changed due to humidity control to the same condition as before the humidity control. For example, when dehumidification is performed, moisture in air is absorbed by a hygroscopic liquid by cooling the hygroscopic liquid of a high solution concentration and passing air through the cooled hygroscopic liquid. This process reduces the solution concentration of the hygroscopic liquid. Sufficient dehumidification cannot be performed with the hygroscopic liquid of a low solution concentration, and thus the hygroscopic liquid is restored to the hygroscopic liquid of a high solution concentration by desorbing moisture from the hygroscopic liquid. On the other hand, when humidification is performed, the solution concentration of the hygroscopic liquid increases, and thus the hygroscopic liquid is restored to the hygroscopic liquid of a low solution concentration by making the hygroscopic liquid absorb moisture.